Interview of Prof. J.-P. Wolf in BBC future

26 janv. 2018
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Wiil we ever have satellites that can control the weather?

By Peter Ray Allison

22 January 2018

From Star Trek to The Jetsons, one of the hallmarks of an advanced civilisation is seen as the ability to control the weather. More recently, the film Geostorm portrayed a network of satellites designed to prevent catastrophic storms.

As last year’s devastating Atlantic hurricanes demonstrated, we are at the mercy of the weather. Could we ever manipulate it from space?

The idea of tweaking the weather from afar is not as far-fetched as it sounds. As BBC Future reported in 2014,
scientists have been on the case for years, albeit using planes rather
than satellites. From 1962 to 1983, the American government ran
Project Stormfury, which was an attempt to weaken tropical storms by flying aircraft into a storm and seeding it with silver iodide.

Silver
iodide is an inorganic compound used as an antiseptic. The theory was
that the silver iodide would cause the supercooled water in the storm to
freeze, thereby disrupting the internal structure of the hurricane.

However, it has since been discovered that
storms do not contain sufficient supercooled water for cloud seeding to
be effective. There was also the problem of scale. “The problem was that
the small planes and macro-scale of the storms meant any attempts would
be negligible,” says Chris Bell, a lecturer in meteorology at the
University of East Anglia in the UK.

Lasers
are also being considered as a form of weather control, through laser
inversion – the technique of using lasers to cool things down rather
than heat them up. The process forms clouds and can even trigger
lightning. “This is a new method based on ultra-fast, ultra-short laser
pulses, which generate intense lasers that are low-energy as the pulse
is very short,” says Jean-Pierre Wolf of the
University of Geneva. This creates a spark in the atmosphere, which causes a shock that expels water droplets out of the way.

However,
the problem, as with cloud seeding, is a question of scale. “We do not
have the right laser and scale of lasers to do something dramatic in the
atmosphere – we can create small cloud formations, but you would not
see the clouds we produce,” admits Wolf. “There is a problem of scaling,
such as creating a cumulous cloud, which is a kilometre long and spans
over tens of kilometres. Then the question is whether it makes sense in
terms of the energy you put into the system.”

If cloud seeding is used, then how satellites are resupplied will present problems

Unfortunately, having satellites control the weather presents additional problems.

Not
only would the satellites need technology onboard to monitor the
weather and position themselves in orbit, they would also need to have
more equipment to manipulate it, thus massively increasing their
payload. “Bringing this kind of equipment onto a satellite always means
huge effort in order to have the mass itself transported into space, and
ensuring the performance and reliability is not easy,” says Andreas
Lindenthal, chief operating officer of
OHB Systems AG and sci-fi enthusiast since his childhood.

If
cloud seeding is used, then how satellites are resupplied will present
problems. Satellites would have to be regularly resupplied with the
necessary materials, which naturally creates logistical problems sending
the resupply craft into space to restock the satellites, which is not
economically viable. “It would be difficult and inefficient,” says
Lindenthal.

Some fear that manipulated weather could be used as a weapon (Credit: Alamy)

Further, as every action has an equal and
opposite reaction, ejecting cloud seeding canisters would tend to nudge
the satellite out of its orbit, due to the reaction forces. It is also
very difficult to get canisters to fall and release in the correct
place, but the addition of guidance systems would add an extra level of
complexity.

Deploying laser inversion via satellites is more
likely. Lasers do not need to be resupplied with materials and their
power demands can be met through solar panels. “There are many examples
in which lasers are being used for a very limited time, which means it
is not in continuous operation,” says Lindenthal. “For example, there
are ideas to remove space debris by flashing them with a laser.”

There
is also the question of what would happen to weather-controlling
satellites following a massive solar storm (also known as a
Carrington-Type Event). When a coronal mass ejection hits the Earth's
magnetosphere, it can cause massive disruption to all electrical
systems. The
Carrington Event,
which is the biggest solar storm on record, occurred in 1859. If and
when a similar event occurred in modern times, all satellites and
satellite-communications are likely to be lost, at least temporarily.
Losing weather control satellites carries with it the risk of
unfortunate meteorological repercussions.

It could be argued that we already manipulate the weather, albeit to our detriment, through climate change

Concerns
have been previously raised that controlling the weather could be used
as a form of economic warfare, as well. During the Vietnam War, a
top-secret project called Operation Popeye was used by the Americans to
disrupt Vietnamese military supplies by increasing rainfall in the
Laotian region through cloud seeding. Following the revelation, there
has been an international ban against weaponising the weather under the
Environmental Modification Convention.

It
could be argued that we already manipulate the weather, albeit to our
detriment, through climate change. However, this shift in weather
patterns was brought about through decades of carbon dioxide and other
greenhouse gases being released into the atmosphere. This has resulted
in changes to the widerworld’s weather patterns, rather than just
isolated regions.

Climate change highlights the scale at which
controlling the weather will need to operate. The colossal size of
weather fronts means that any effective weather modification system
would require agreement on a global scale. There is also the danger that
mitigating storms in one region could result in storms being created
elsewhere.

US forces tried to disrupt North Vietnamese supply line in the Vietnam War with attempts to increase rainfall (Credit: Alamy)

For now, controlling the weather remains
unlikely – too costly and resource-hungry to make practical. “People are
putting research into very efficient lasers that can be put into
orbit,” says Lindenthal. “For me, itis only a matter of time.”

“We may, one day, have the technology to control the weather,” adds Bell, “but it will be in thousands, not hundreds, of years.”